Various insults to the eye lens have been correlated with cataract formation. For instance, UV light, radiation, poor nutrition, diabetes, steroid administration and estrogen deficiency have been associated with increased prevalence of cataracts. Senile cataracts may be the result of one or more of these and other factors. One goal of this laboratory is to determine the expressed gene changes in cataract lenses that may be actively involved in cataract formation. Reverse transcriptase polymerase chain reaction differential display (RT-PCR DD or DD) is a technique that compares the levels of expressed genes between two conditions. This method has been used by our laboratory to analyze expressed genes in the lens. DD of human epithelia from normal and cataract lenses have revealed a number of genes unique to cataract lenses. In addition, densitometric quantitation has indicated an upregulation of several genes in cataracts from 4-to 10-fold. One of these genes has been identified by sequencing as serine/threonine phosphatase. DD is also being used to analyze the levels of expressed genes in human lens epithelial cells in culture under oxidative stress, a widely used model for human senile cataracts. Over 25 genes have been observed to change in these cells. Three genes, verified by Northern blot to be downregulated over 10-fold in stressed cells, are or particular interest because of their impact on cell homeostasis. Two of these genes, NADH dehydrogenase and cytochrome b are involved in mitochondrial respiration, while the third gene, glutamine cyclase, is involved in peptide processing. Information obtained in the above studies will be used to identify associations between these genes and subtypes of human cataracts.